A. Field of the Invention
The present invention relates to a face mask assembly for a person, and more particularly to a face mask having a replaceable filter adjacent to a person's facial breathing area and also other features directed toward sanitary use of the face mask and comfortable and effective use of a face mask, and also to a method of using the same.
Background Art
The are many working environments in which it is necessary (or at least desirable) for a person to wear a face mask or other apparatus to filter the air which the person is breathing. In addition to the expected problems of arranging the filtering mechanism or other air purifying device so that it operates effectively, there are considerations relative to sanitation, ergometrics, convenience of use, and the person's comfort in allowing the breathing process to be as natural as possible. These problems or considerations are exacerbated to some extent when the mask is being worn in a situation where the person wearing the mask is doing active work that requires the person to breath air at a greater volumetric rate. For example, under these circumstances, in addition to being able to filter the air at a greater rate of volumetric flow, there may be greater condensation of moisture from the air which the person is exhaling. Also, many prior art face masks create a feeling of "stuffiness" or other type of discomfort, or some actual impediment to, or alteration of, the normal breathing process. Yet, in designing face masks to alleviate these problems, it is also desirable to make the face mask light weight, compact, economical in operation as well as manufacture, convenient to use, and also compatible with a variety of physical movements a person might be expected to perform in various tasks.
Another important consideration relates to sanitation, in that the same face mask may be worn by different persons at different times. Not just the breathing of the person, but possibly even the coughing or sneezing of the person wearing the mask could be a source of contamination that might be passed on to a person wearing the mask at a subsequent time. While ideally the face mask should be sanitized or sterilized in some manner before being worn by another, or possibly a procedure could be implemented where each person would have his or her own personalized mask which would not be used by another, such procedures may not be practical or properly adhered to. One general approach that is used in a variety of situations as a sanitation technique (e.g. a number of items used in hospital operations) is to simply make the item inexpensively and dispose of the item after its initial use. However, many items having more than a minimum of sophistication do not lend themselves to this approach.
A searching of prior art patents and literature has developed a number of items, these being listed below.
British patent specification 1,049,604 (Klavdienko) shows a "dustproof respirator" which comprises an airtight mask 1 made of an elastic material (e.g. rubber) that is held on a person's face by means of a tape 10. The mask 1 appears to comprise a planar wall having a folded elastic cuff 4 that is made integral with the mask 1 and extends around the perimeter thereof. An inlet valve 2 is formed apparently at the middle of the wall of the mask 1, and an outlet valve 3 is formed at a bottom part of the mask 1. It appears that the mask 1 defines substantially the entire enclosure which isolates a portion of the person's face from the ambient atmosphere. Extending forwardly from the mask 1 is what is called a "distance plate 8" having a rear portion adjacent to the inlet valve 2 and a forward portion. It is stated that the distance plate 8 is "a perforated easily bent distance plate 8", and it would appear to be formed as a cylinder, whose axes extends forwardly from the inlet valve 2. There is an outer coarse filter 5 within which is positioned an inner fine filter 6, these being closely adjacent to one another and having the shape of a cup. The perimeter portion of these filters 5 and 6 are connected to the cuff 4 of the mask, and the central portion of these filters 5 and 6 are positioned at the forward part of the distance plate 8. Thus, it appears that the mask 1 with the valves 2 and 3 define substantially all of the surface area and in turn defines the chamber or space that is directly adjacent to the person's face and breathing area, while the two filter elements 5 and 6 are positioned outside of the chamber defined by the mask 1. It is stated that the inner fine filter 6 is changeable. In operation, outside air passes first through the coarse filter 5, and then through the inner filter 6 and thence into the inlet valve 2 so as to pass into the chamber defined by the mask 1 so that this air can be breathed in by the person. (It may be that the air actually passes through the perforated distance plate 8 before passing into the inlet valve 2). Then when the person exhales, the exhaled air passes from the chamber defined by the mask 1 out the valve 3.
U.S. Pat. No. 4,090,510 (Segersten) discloses a "Face Mask With a Changeable Filter". The mask 1 is made of leather or the like and has a number of holes which are punched out to admit air. The filter is made of two layers, namely a layer or sheet 7 made of a suitable cellulose to intercept coarse particles and a similar piece 8 to intercept fine particles. To form the filter, the sheet 8 is placed on the sheet 7 and then the sheet or filter 7 is folded over with the seam 9 made so that the filter has an outside part 7 and an inside part 8. This resulting filter is joined to the mask 1 by means of two metal bands 11 fitting on the side of the mask 1.
U.S. Pat. No. 4,866,056 (Simpson) discloses a "breathing apparatus where there is a mask 2 that is called an `orinasal mask`. This mask 2 has an inhale valve 8 and an exhale valve positioned on the opposite side of the mask 2, but not shown. There is a pressure sensing element 9 which responds to the person exhaling, and when the person exhales, a fan which draws air into the mask is shut off.
U.S. Pat. No. 5,022,900 (Bar-Yona et al) shows a particular configuration of a ventilation filtration device. There is a centrifugal type rotor and the filter extends at least in an annular configuration up along side the rotor.
U.S. Pat. No. 5,003,974 (Mou) shows an emergency breathing mask which is transparent and is placed over the user's head. There is a flexible air pipe feeding air into the transparent container from a case 2.
U.S. Pat. No. 4,971,052 (Edwards) shows a motor driven fan which draws air through a filter 16. The motor is controlled by a switch means that responds to pressure variations as the user breathes.
U.S. Pat. No. 4,549,542 (Chien) shows a breathing mask in which a motor drives a series of fans. One set of blades directs the air into the breathing area and a second set sucks the air from the breathing space. There may be a filter section 22 that filters the air that is drawn in.
U.S. Pat. No. 4,502,480 (Yamaoto) shows a breathing aid for motorcycle riders in which there is a hose that carries air from a filter placed on the front of the bike. There may be a filter element in the fan as shown in FIG. 2.
U.S. Pat. No. 4,478,216 (Dukowski) shows a breathing filter with a face mask. There is a fan which propels air through the filter.
U.S. Pat. No. 4,430,995 (Hilton) shows a filtering breathing mask in which there is a fan means that supplies air to a resilient air storage bag 13.
U.S. Pat. No. 4,331,141 (Pokhis) shows a breathing arrangement where there is a deformable container on the person's thorax so that when the person breathes in so that the volume of the thorax increases, the container is deformed and the volume of the inner chamber decreases so that ambient air which enters the inner chamber of the container is urged to flow through the filter system.
U.S. Pat. No. 4,320,755 (Flint et al) shows a breathing mask filter system in which a fan 10 drives the air through a filtering element 13. Patentability seems to be directed toward specific mechanical features.
U.S. Pat. No. 3,736,927 (Misaqi) shows a breathing aid in which a motor powered fan blows filtered and conditioned air between the user's face and the shield.
U.S. Pat. No. 3,525,334 (Braman et al) shows a cleanroom suit in which there is an air supply means 51 that includes a fan to supply air to the user. There is a filter element that filters the air as it leaves the suit so that the dust and like are removed from the exhaled air.
U.S. Pat. No. 4,646,732 (Chien) shows a respiratory mask where there is a fan 4b for drawing air through what appears to be a filter in a canister 8, and delivers this air through the passageway 43 into the interior of the mask. There is an exhaust fan 6b that draws the air from the interior of the mask and discharges it outwardly through an exhaust vent 61c.
British Pat. No. 222 366 (Davis) relates to "gas mask and particularly to masks commonly known as double mask" (first page, column 1, line 60 and following). The inner mask a covers the nose and mouth to form a gas-tight joint, and it has inlet valves k1 that lead from the space h between the inner mask a and outer mask b into the area within the inner mask. There is an outlet valve leading from inside the inner mask to the outside atmosphere. The person exhales from the inner mask a through the tube m and out a check valve 1. The incoming air enters from a source or supply through the tube j and thence through the openings n into the area h. It is stated (page 2, column 1, line 62) that the inner mask is connected at c by cement. It does not appear that this inner mask a functions as a filter since air enters the inner mask area by valves k1.
British Pat. No. 2,044,110 (Gdulla) shows a respiratory mask rather similar in overall design to the aforementioned to Davis British Patent (No. 222,366). the inhaled air passes upwardly through the tube 1 and through the valve 11 into the inner mask 10. The exhaled air goes through a check valve 14 leading downwardly from the inner mask and also extending through the outer mask.
German Pat. No. 1,285,893 which has a removeable inner mask, but the inner mask is not in the form of a secondary filter.
British Pat. No. 2,173,705 (Howie) discloses a mask having a filter where there is a fan that draws the air through the filter. It is arranged so that the fan 9 can be interposed between the filter and the mask inlet, or the filter may be connected directly to the mask.
British Pat. No. 2,222,777A (Simpson) is another example of a filter for a respiratory device that has a motor driven fan drawing air into the filter.
British Pat. No. 2,215,217 (Simpson) shows a pressure filter respirator similar to the other Simpson patent (British 2,222,777A) where there is a motor driven fan. There is a curved wall 10 within the mask to direct the air into an upper portion of the face mask.
British Pat. No. 2,109,246 (Shyn et al) is yet another example of a mask having a motor to drive a compressor to draw the air through the filter.
British Pat. No. 2,215,216 (Simpson) shows a mask similar to that shown in the other Simpson Patent (British Pat. #2,215,217A), but in the '216 patent there is shown an alarm system to indicate when the pressure within the mask has declined to too low of a level.
British Pat. No. 2,209,474A shows a respirator where there is a fan that draws air through a filter unit 10 having a replaceable filter 11.
European patent application no. 0,130,707 (O'Connor) shows a breathing apparatus where there is a fan drawing air through a filter cannister 11 and directing it through a hose 4 to a mask. The mask has an inner mask with an inlet valve and an outlet valve.
European Patent application no. 0,094,757 (O'Connor) shows a pressure respirator substantially the same as that shown in European Patent 0,130,707. This patent focuses more on the concept of having the inlet valve arranged so that when the person is exhaling, even though the fan continues to operate, there is substantially no air moved into the mask.
Finally, there is shown one page of an advertisement entitled "Light weight respirator mask has self-contained blower".